Corpora allata

Definition

Paired endocrine glands located behind the brain in the head of insects (and some other arthropods) that synthesize and secrete juvenile hormone (JH), a sesquiterpenoid that maintains the larval or nymphal state and suppresses metamorphosis. By modulating JH titer, the corpora allata govern the timing of molts, the nature of each molt (larval-larval versus larval-pupal or nymphal-adult), and reproductive maturation in adults. Their activity is regulated by neuropeptides (allatostatins and allatotropins) from the brain and by feedback from the developing gonads.

Etymology

Latin: corpus (body) + allatum (carried to), referring to their position behind the brain

Example

In the tobacco hornworm (Manduca sexta), the corpora allata are inactive during the final larval instar, allowing juvenile hormone levels to drop; this decline permits the molt to the pupal stage. Artificially maintaining high JH by implanting active corpora allata from a young larva blocks this transition, producing a supernumerary larval instar or 'giant larva.'

Synonyms

• CA

Related Terms

• Juvenile hormone
• corpus cardiacum
• prothoracic gland
• Ecdysone
• Metamorphosis
• allatostatin
• allatotropin
• retrocerebral complex

Usage Notes

The singular form 'corpus allatum' refers to one gland of the pair; 'corpora allata' refers to both glands together, which is the more common usage in experimental contexts because the glands function as a unit and are often manipulated or assayed together. The glands are anatomically distinct from the adjacent corpus cardiacum, which stores and releases brain-derived neuropeptides including those that regulate the corpora allata. In some insects (e.g., higher Diptera), the corpora allata fuse into a single median structure, but the plural term persists in the literature. The abbreviation 'CA' is widely used in endocrinology literature but should be defined on first use to avoid confusion with other abbreviations.